49. Basic Drugs and Principles of Intensive Therapy for Bronchial Asthma

Stepwise Approach to Acute Asthma / Status Asthmaticus

First-Line (All Patients)

Second-Line (Moderate–Severe / Refractory)

Intensive Care Measures (Life-Threatening)

• High-flow oxygen — titrate SpO₂ to 93–95%
• NIV (BiPAP) — consider in hypercapnic respiratory failure before intubation
• Mechanical ventilation — last resort; use low RR (10–14/min), prolonged expiratory time (I:E = 1:3–4), low PEEP to prevent air trapping (permissive hypercapnia acceptable)
• Ketamine — 1–2 mg/kg IV induction agent of choice for intubation (bronchodilatory effect)
• Volatile anesthetics (isoflurane, sevoflurane) — rescue bronchodilation in ICU via anesthetic machine

General Principles

1. Treat hypoxemia first (oxygen supplementation)
2. Aggressive inhaled bronchodilators — continuous nebulization if needed
3. Corticosteroids early — reduce hospital duration and relapse
4. Identify and treat triggers (allergens, infection, NSAIDs)
5. Monitor with peak flow / spirometry, ABG (PaCO₂ rising in severe attack = impending respiratory failure)
6. Avoid sedatives (suppress respiratory drive), beta-blockers, NSAIDs

50. Principles of Treatment of Cardiac Asthma and Acute Pulmonary Edema

Pathophysiology Rationale

Treatment Pillars

1. Reduce Preload

• Nitrates (nitroglycerin/isosorbide dinitrate) — venodilation reduces venous return; sublingual 0.4 mg q5 min, then IV infusion 10–200 µg/min
• Furosemide (loop diuretic) — IV 40–80 mg bolus (also has early venodilatory effect before diuresis begins); reduces circulating volume
• Morphine — 2–5 mg IV; reduces sympathetic tone, anxiolysis, venodilation (use cautiously; may cause respiratory depression)

2. Reduce Afterload

• IV nitroprusside — potent arteriolar + venodilator; used in hypertensive pulmonary edema (titrate carefully, monitor for cyanide toxicity)
• ACE inhibitors — acute IV enalaprilat in hypertensive heart failure

3. Improve Oxygenation and Ventilation

• High-flow O₂ — target SpO₂ ≥ 95%
• CPAP/BiPAP (NIV) — CPAP 5–10 cmH₂O improves oxygenation, reduces work of breathing, decreases preload; first-line respiratory support in cardiogenic pulmonary edema
• Intubation + mechanical ventilation — if refractory hypoxemia (PaO₂ < 60 mmHg on max O₂), exhaustion, or altered consciousness

4. Improve Cardiac Output (when cardiac output is low)

• Dopamine — 2–5 µg/kg/min (dopaminergic); 5–10 µg/kg/min (inotropic)
• Dobutamine — 2–20 µg/kg/min; preferred inotrope in low-output failure
• Levosimendan — calcium sensitizer; used in acute decompensated HF

5. Treat Underlying Cause

• Arrhythmia → cardioversion / antiarrhythmics
• Hypertensive crisis → rapid BP reduction
• ACS → antiplatelet, heparin, revascularization
• Valvular disease → surgical/interventional correction

51. Algorithm for Emergency Care During an Attack of Cardiac Asthma

STEP 1 — IMMEDIATE POSITIONING
  ↓
• Sitting upright (legs dangling — reduces preload passively)
• Call for emergency support, IV access × 2

STEP 2 — OXYGEN THERAPY
  ↓
• High-flow O₂ via face mask 8–10 L/min → titrate SpO₂ ≥ 95%
• If SpO₂ < 90% despite O₂ → start CPAP 5–10 cmH₂O immediately

STEP 3 — NITRATES (if SBP > 100 mmHg)
  ↓
• Nitroglycerin sublingual 0.4 mg → repeat every 5 min × 3
• If IV access: start IV nitroglycerin 10–20 µg/min, titrate up

STEP 4 — DIURETIC
  ↓
• Furosemide 40–80 mg IV bolus (higher dose if on chronic furosemide)
• Monitor urine output

STEP 5 — MORPHINE (optional, use cautiously)
  ↓
• Morphine 2–5 mg IV slowly
• AVOID if: hypotension, bradycardia, COPD, altered consciousness

STEP 6 — MONITOR & REASSESS (every 15–30 min)
  ↓
• SpO₂, HR, BP, RR, urine output
• ABG if available
• 12-lead ECG to identify precipitant (ACS, arrhythmia)

STEP 7 — ESCALATION IF NO IMPROVEMENT
  ↓
• Increase IV nitroglycerin or add IV nitroprusside
• Start inotropes if SBP < 90 mmHg (dopamine/dobutamine)
• Intubation + mechanical ventilation if:
    – SpO₂ < 88% on max O₂/CPAP
    – PaCO₂ rising, acidosis (pH < 7.20)
    – Exhaustion, loss of consciousness

STEP 8 — TREAT PRECIPITANT
  ↓
• ACS → anticoagulation, aspirin, urgent revascularization
• Rapid AF → rate control (digoxin, amiodarone), cardioversion
• Hypertensive crisis → IV labetalol, nitroprusside

52. Principles of Treatment of Chronic Obstructive Pulmonary Disease (COPD)

Stable COPD (GOLD Strategy)

A. Pharmacotherapy — Stepwise

• LAMA (Tiotropium, Aclidinium, Glycopyrronium) — reduce exacerbations, improve exercise tolerance
• LABA (Salmeterol, Formoterol, Indacaterol) — sustained bronchodilation
• LAMA + LABA combination — superior to monotherapy in symptomatic patients

• Inhaled corticosteroids (ICS) — NOT first-line monotherapy; add to LAMA+LABA if: eos ≥ 300/µL, or ≥ 2 exacerbations/year, or history of asthma
• Roflumilast — PDE-4 inhibitor; add in severe COPD with chronic bronchitis + frequent exacerbations
• Azithromycin (long-term, low-dose) — reduces exacerbation frequency in selected patients

B. Non-Pharmacological

• Smoking cessation — single most effective intervention; slows FEV₁ decline
• Pulmonary rehabilitation — improves exercise capacity and quality of life
• Long-term oxygen therapy (LTOT) — PaO₂ ≤ 55 mmHg (or ≤ 60 mmHg with cor pulmonale/polycythemia); ≥ 15 h/day; only intervention proven to improve survival
• Vaccinations — influenza (annual), pneumococcal, COVID-19
• Surgical — bullectomy, lung volume reduction surgery (LVRS), lung transplant in selected patients

Acute Exacerbation of COPD (AECOPD)

Treatment Protocol

• SABA (salbutamol) + SAMA (ipratropium) via nebulizer — first-line
• Increase frequency and dose during exacerbation

• Prednisolone 40 mg/day PO × 5 days (equivalent to longer courses)
• Reduce treatment failure, improve FEV₁, shorten hospitalization

• Indications: increased sputum purulence + increased dyspnea + increased sputum volume (Anthonisen criteria), or requiring mechanical ventilation
• Amoxicillin-clavulanate, doxycycline, or azithromycin (5–7 days); fluoroquinolones in severe/Pseudomonas risk

• Target SpO₂ 88–92% (NOT high-flow — risk of hypercapnic respiratory failure by abolishing hypoxic drive)
• Controlled O₂ via Venturi mask (24–28%)

• Indications: acute hypercapnic respiratory failure (pH < 7.35, PaCO₂ > 45 mmHg), RR > 25
• Reduces intubation rate and mortality
• Settings: IPAP 12–20 cmH₂O, EPAP 4–8 cmH₂O

• If NIV fails or contraindicated
• Permissive hypercapnia, low tidal volumes

• Thromboprophylaxis (heparin)
• Nutritional support
• Treat comorbidities (heart failure, PE, pneumonia)

Sources: Harrison's Principles of Internal Medicine, 21st Ed. (p. 8301); Pediatric Critical Asthma guidelines (p. 16); GOLD 2023 COPD Guidelines; BTS/NICE Acute Asthma Guidelines; ESC Acute Heart Failure Guidelines 2021.